@misc{ScholzSchmidt, author = {Scholz, Tanja and Schmidt, Peer}, title = {Homogeneity Range of the Zirconium Phosphide Telluride Zr2+xPTe2 and the High Temperature Phase Transformation to Zr2PTe}, series = {European Journal of Inorganic Chemistry}, journal = {European Journal of Inorganic Chemistry}, number = {8}, issn = {1099-0682}, doi = {10.1002/ejic.201403043}, pages = {1457 -- 1462}, abstract = {The synthesis of the phosphide telluride Zr2+xPTe2 was accomplished by a solid-state reaction from the elements. Le Bail refinements of the as synthesized crystalline powders as well as the thermal decomposition of Zr2PTe2 along the homogeneity range Zr2+xPTe2 under the release of P4(g) and Te2(g) evidences a maximum zirconium content according to the composition Zr2.5PTe2. The thermal decomposition product of Zr2.5PTe2 undergoes a phase transformation to "Zr2PTe" adopting the structure motive of the binary phases ZrTe and ZrTe2. The new phase "Zr2PTe" has a wide homogeneity range Zr2-xP1-yTe1+y tolerating a deficit in the cation position and a mixed occupation of the anions. The composition of the crystalline decomposition product was determined to Zr1.95P0.84Te1.16 by Rietveld refinement and by analysing the elemental composition with ICP-OES. Zr1.95P0.84Te1.16 crystallizes in hexagonal space group P63/mmc (no. 194) with lattice constants: a = 3.8726(1) {\AA} and c = 13.008(1) {\AA}.}, language = {en} } @misc{BachhuberAppenDronskowskietal., author = {Bachhuber, Frederik and Appen, J{\"o}rg von and Dronskowski, Richard and Schmidt, Peer and Nilges, Tom and Pfitzner, Arno and Weihrich, Richard}, title = {Van der Waals interactions in selected allotropes of phosphorus}, series = {Zeitschrift f{\"u}r Kristallografie}, volume = {230}, journal = {Zeitschrift f{\"u}r Kristallografie}, number = {2}, issn = {2196-7105}, doi = {10.1515/zkri-2014-1800}, pages = {107 -- 115}, abstract = {Selected allotropes of phosphorus are investigated by different levels of density functional theory (DFT) calculations to evaluate the relative stability orders with a special focus on the role of van der Waals interactions.Phosphorus is an excellent reference system with a large number of allotropes. Starting from low-dimensional molecular (0D, white P) and polymer structures (1D, P nanorods) to layered (2D, black P) and tubular structures (2D and 3D, crystalline forms of red P), covalent structure motifs are interconnected by van der Waals interactions. They are a key factor for the correct energetic description of all P allotropes. A comparative study is carried out within the local density approximation (LDA) and the generalized gradient approximation (GGA), with and without implementation of a dispersion correction by Grimme (GGA-D2). Our intention is to achieve a reasonable agreement of our calculations with experimental data, the plausibility of energy values, and the treatment of long-range interactions. The effect of van der Waals interactions is exemplified for the interlayer distances of black phosphorous and its electronic structure.}, language = {en} } @misc{BachhuberAppenDronskowskietal., author = {Bachhuber, Frederik and Appen, J{\"o}rg von and Dronskowski, Richard and Schmidt, Peer and Nilges, Tom and Pfitzner, Arno and Weihrich, Richard}, title = {The Extended Stability Range of Phosphorus Allotropes}, series = {Angewandte Chemie / International edition}, volume = {53}, journal = {Angewandte Chemie / International edition}, number = {43}, issn = {1521-3773}, doi = {10.1002/anie.201404147}, pages = {11629 -- 11633}, abstract = {Phosphorus displays fascinating structural diversity and the discovery of new modifications continues to attract attention. In this work, a complete stability range of known and novel crystalline allotropes of phosphorus is described for the first time. This includes recently discovered tubular modifications and the prediction of not-yet-known crystal structures of [P12] nanorods and not-yet-isolated [P14] nanorods. Despite significant structural differences, all P allotropes consist of covalent substructures, which are held together by van der Waals interactions. Their correct reproduction by ab initio calculations is a core issue of current research. While some predictions with the established DFT functionals GGA and LDA differ significantly from experimental data in the description of the P allotropes, consistently excellent agreement with the GGA-D2 approach is used to predict the solid structures of the P nanorods.}, language = {en} } @misc{OstersNilgesSchoeneichetal., author = {Osters, Oliver and Nilges, Tom and Sch{\"o}neich, Michael and Schmidt, Peer and Rothballer, Jan and Pielnhofer, Florian and Weihrich, Richard}, title = {Cd4Cu7As, the first representative of a fully ordered, orthorhombically distorted MgCu2 Laves phase}, series = {Inorganic Chemistry}, volume = {51}, journal = {Inorganic Chemistry}, issn = {1520-510X}, doi = {10.1021/ic3005213}, pages = {8119 -- 8127}, abstract = {The ternary Laves phase Cd4Cu7As is the first intermetallic compound in the system Cu-Cd-As and a representative of a new substitution variant for Laves phases. It crystallizes orthorhombically in the space group Pnnm (No. 58) with lattice parameters a = 9.8833(7) {\AA}; b = 7.1251(3) {\AA}; c = 5.0895(4) {\AA}. All sites are fully occupied within the standard deviations. The structure can be described as typical Laves phase, where Cu and As are forming vertex-linked tetrahedra and Cd adopts the structure motive of a distorted diamond network. Cd4Cu7As was prepared from stoichiometric mixtures of the elements in a solid state reaction at 1000 °C. Magnetic measurements are showing a Pauli paramagnetic behavior. During our systematical investigations within the ternary phase triangle Cd-Cu-As the cubic C15-type Laves phase Cd4Cu6.9(1)As1.1(1) was structurally characterized. It crystallizes cubic in the space group Fd3m̅ with lattice parameter a = 7.0779(8) {\AA}. Typically for quasi-binary Laves phases Cu and As are both occupying the 16c site. Chemical bonding, charge transfer and atomic properties of Cd4Cu7As were analyzed by band structure, ELF, and AIM calculations. On the basis of the general formula for Laves phases AB2, Cd is slightly positively charged forming the A substructure, whereas Cu and As represent the negatively charged B substructure in both cases. The crystal structure distortion is thus related to local effects caused by Arsenic that exhibits a larger atomic volume (18 {\AA}3 compared to 13 {\AA}3 for Cu) and higher ionicity in bonding.}, language = {en} } @misc{ScholzDaoQuocSchmidt, author = {Scholz, Tanja and Dao Quoc, Huong and Schmidt, Peer}, title = {Phase barograms - phased diagrams of vapour pressure: Eutectoid Phase Formation in Binary Systems}, series = {Thermochimica Acta}, volume = {541}, journal = {Thermochimica Acta}, doi = {10.1016/j.tca.2012.04.022}, pages = {1 -- 7}, abstract = {Phase barograms are specific representations of conventional (x, T) phase diagrams considering the vapor pressure as additional thermodynamic parameter. Thus, the determination of the vapor pressure is complementary to conventional DTA or DSC measurements. A stringent relationship between the phase diagram and the corresponding phase barogram is derived by thermodynamic considerations of phase relations for complex heterogeneous equilibria. For that purpose, a derivative of the three-dimensional Clausius-Clapeyron equation is utilized. As a result, a validation of DTA/DSC measurements becomes feasible by the transformation of characteristic effects of vapor pressure measurements into thermal effects in conventional phase diagrams. The system CsBr/SeO2 is presented as a case study of systems with a eutectoid phase formation. CsSeO2Br is formed from the binaries at ϑf = 180(5) °C; the compound decomposes peritectically at ϑp = 470(10) °C.}, language = {en} } @misc{GuentherBeckmannSchoeneichetal., author = {G{\"u}nther, David and Beckmann, Jens and Sch{\"o}neich, Michael and Schmidt, Peer and Klepel, Olaf}, title = {Porous concrete as a template for the synthesis of porous carbon materials}, series = {Carbon}, volume = {50}, journal = {Carbon}, number = {8}, issn = {0008-6223}, doi = {10.1016/j.carbon.2012.02.039}, pages = {3092 -- 3116}, abstract = {The potential of industrial porous concrete for using as a template for the synthesis of porous carbon materials has been investigated. Carbon replicas of porous concrete have been prepared by carbonization of sucrose. The pores of the resulting carbon materials range from the macropore to the micropore region, pointing to a hierarchy.}, language = {en} } @misc{SchmidtSchoeneichBawohletal., author = {Schmidt, Peer and Sch{\"o}neich, Michael and Bawohl, Melanie and Nilges, Tom and Weihrich, Richard}, title = {Thermal analysis detecting equilibrium conditions: The use of the high temperature gas balance for thermogravimetric measurements}, series = {Journal of Thermal Analysis and Calorimetry}, volume = {110}, journal = {Journal of Thermal Analysis and Calorimetry}, number = {3}, issn = {1572-8943}, doi = {10.1007/s10973-011-2107-3}, pages = {1511 -- 1521}, abstract = {Several methods are established in thermal analysis to investigate phase formation, phase transition, and decomposition reactions. The analysis of phase equilibria with volatile components is particularly feasible by using standard method of thermogravimetry. Hardly any investigations of phase formation reactions are possible to realize if one of the components is lost by vaporization. By using the "High-Temperature Gas-Balance" (HTGB), the vapor phase is enclosed in a silica ampoule and thus forms an equilibrium gas phase in permanent contact with the solid phase. The measurement signal Δmmeas is caused by change of the leverage of the horizontal balance support during evaporation and condensation. The application of the HTGB allows the analysis of solid-gas equilibria in the working range from 0.01 till 15 bar at temperatures up to 1,100 °C. The first comparison of evaporation reactions determined by standard thermogravimetric analyses and by measurements using the HTGB is given for the inorganic systems: P, As, SeO2, PtI2, and Hg/I.}, language = {en} } @misc{OstersNilgesBachhuberetal., author = {Osters, Oliver and Nilges, Tom and Bachhuber, Frederik and Pielnhofer, Florian and Weihrich, Richard and Sch{\"o}neich, Michael and Schmidt, Peer}, title = {Synthesis and Identification of Metastable Compounds: Black Arsenic—Science or Fiction?}, series = {Angewandte Chemie / International edition}, volume = {51}, journal = {Angewandte Chemie / International edition}, number = {12}, issn = {1521-3773}, doi = {10.1002/anie.201106479}, pages = {2994 -- 2997}, abstract = {Back in black: All metastable and stable phases can be identified for the solid solution arsenic/phosphorus by a combination of quantum-chemical calculations and investigations of the phase formation. Reaction paths for phase formations and transitions in situ were also evaluated. The results show that orthorhombic black arsenic (o-As) is metastable in pure form and has only been previously obtained by stabilizing impurities.}, language = {en} } @misc{RudorfSchmidt, author = {Rudorf, Wolfram W. and Schmidt, Peer}, title = {Studies on synthetic galloalunites AGa3(SO4)2(OH)6: Synthesis, Thermal analysis, and X-ray characterization}, series = {Thermochimica Acta}, volume = {521}, journal = {Thermochimica Acta}, number = {1-2}, doi = {10.1016/j.tca.2011.04.013}, pages = {112 -- 120}, abstract = {Stoichiometric end member galloalunites of the general formula AGa3(SO4)2(OH)6, with A = Na+, K+, Rb+, H3O+, and NH4+ have been synthesized under hydrothermal conditions. These galloalunites were characterized by chemical methods, thermal analysis (DSC, TG coupled with mass spectroscopy), and powder X-ray diffraction (XRD). The stages of thermal decomposition of sodium, potassium and rubidium galloalunite show a common decomposition mechanism forming β-Ga2O3 and A2SO4 (A = Na+, K+, and Rb+) while ammonium and oxonium galloalunite decompose under formation of pure β-Ga2O3. The thermogravimetric results confirmed the analytical results on the galloalunites and thereby verified the stoichiometry of these synthetic products. Galloalunites with different monovalent cations in A site (i.e. Na+, K+, Rb+, H3O+ and NH4+) crystallize in the rhombohedral space group R-3m (\#166). The effects of substitution on the unit cell parameters are rationalized in terms of the structural arrangements in galloalunites. The unit cell parameter c increases with increasing effective ionic radii of the cation in the A site, whereas the parameter a changes to a much lesser degree.}, language = {en} } @misc{ZhangHerklotzHieckmannetal., author = {Zhang, Xi and Herklotz, Frank and Hieckmann, Ellen and Weber, J{\"o}rg and Schmidt, Peer}, title = {Vapor phase growth of ZnO single crystals}, series = {Journal of Vacuum Science and Technology : A}, volume = {29}, journal = {Journal of Vacuum Science and Technology : A}, doi = {10.1116/1.3553461}, pages = {03A107}, abstract = {Zinc oxide is a promising wide band gap semiconductor for future optoelectronic devices. Today ZnO bulk single crystals are grown by three different techniques: hydrothermally, from the melt, and by chemical vapor transport. For our studies, the authors employed in addition a simple and low cost vapor phase method which gives us good quality crystals and flexibility in crystal doping. The as-grown needle-shaped single crystals were characterized by resistivity measurements, scanning electron microscopy, electron backscatter diffraction, and low temperature photoluminescence spectroscopy.}, language = {en} } @misc{TschulikHoffmannFokwaetal., author = {Tschulik, Kristina and Hoffmann, Stefan and Fokwa, Boniface P. T. and Gilleßen, Michael and Schmidt, Peer}, title = {Studies regarding the homogeneity range of the zirconium phosphide telluride Zr2+xPTe2}, series = {Solid State Sciences}, volume = {12}, journal = {Solid State Sciences}, number = {12}, issn = {1293-2558}, doi = {10.1016/j.solidstatesciences.2010.08.022}, pages = {2030 -- 2035}, abstract = {The phosphide tellurides Zr2+δPTe2 (0 ≤ δ ≤ 1) can be synthesized from the elements in a solid state reaction or by thermal decomposition of Z. Zr2PTe2 decomposes under release of Te2(g) + P4(g) forming the homogeneity range Zr2+δPTe2. The growth of single crystals of Zr2+δPTe2 succeeded by chemical vapour transport using iodine as transport agent from 830 °C in direction of higher temperatures up to 900 °C. Zr2+δPTe2 crystallizes in the rhombohedral space group R-3m (no. 166) with lattice parameters a = 383(1)…386(1) pm and c = 2935(4)…2970(4) pm for δ = 0…1, respectively. Single crystal data have been determined for Zr2.40(2)PTe2 with lattice parameters a = 385.24(4) pm and c = 2967.8(4) pm. The electronic structure and chemical bonding in Zr2+δPTe2 was investigated by the linear muffin-tin orbital (LMTO) method. Both Zr2PTe2 and Zr3PTe2 show non-vanishing DOS values at the Fermi level (EF) indicating metallic character. According to COHP bonding analyses, mainly the heteroatomic Zr-P and Zr-Te bonds are responsible for the structural stability of Zr3PTe2. The new Zr2-Te bond, which is not present in Zr2PTe2, is stronger than Zr1-Te and is thought to be responsible for the stability of phases having Zr in excess.}, language = {en} } @misc{SchoeneichSchmidtSchmidt, author = {Sch{\"o}neich, Michael and Schmidt, Marcus P. and Schmidt, Peer}, title = {Chemical Vapour Transport of Bismuth and Antimony Chalcogenides M2Q3 (M = Sb, Bi, Q = Se, Te)}, series = {Zeitschrift f{\"u}r anorganische und allgemeine Chemie}, volume = {636}, journal = {Zeitschrift f{\"u}r anorganische und allgemeine Chemie}, number = {9-10}, issn = {1521-3749}, doi = {10.1002/zaac.201000149}, pages = {1810 -- 1816}, abstract = {Thermodynamic modelling of the ternary systems M/Q/I (M = Sb, Bi, Q = Se, Te) indicated solid-gas equilibria suitable for chemical vapour transport of bismuth and antimony chalcogenides. The predictions of the modelling were confirmed by transport experiments on a transport balance. The optimum transport conditions using iodine as transport agent were determined for all systems to: ϑsource = 500 °C and ϑsink = 450 °C. For ΔT > 50 K the sequential transport of chalcogenide iodides MQI followed by M2Q3 occurs. Thermodynamic standard data of the gas species SbI(g) were concluded from equilibrium calculations: ΔH0f,298(SbI(g)) = 106 ± 3 kJ·mol-1; S0298(SbI(g)) = 255 ± 3 J·mol-1·K-1; Cp(SbI(g)) = 37 ± 1 J·mol-1·K-1}, language = {en} } @misc{JahnBlaudeckBaumannetal., author = {Jahn, Stephan F. and Blaudeck, Thomas and Baumann, Reinhard R. and Jakob, Alexander and Ecorchard, Petra and R{\"u}ffer, Tobias and Lang, Heinrich and Schmidt, Peer}, title = {Inkjet Printing of Conductive Silver Patterns by Using the First Aqueous Particle-Free MOD Ink without Additional Stabilizing Ligands}, series = {Chemistry of Materials}, volume = {22}, journal = {Chemistry of Materials}, number = {10}, issn = {1520-5002}, doi = {10.1021/cm9036428}, pages = {3067 -- 3071}, abstract = {The chemical and physical properties of [AgO2C(CH2OCH2)3H] (3) and its use as an aqueous, ligand-free MOD ink (MOD = metal-organic decomposition) for piezo inkjet printing is discussed. The printed, thermal, or photochemical sintered silver features are electrically conductive on glass (2.7 × 107 S m-1) and PET (PET = polyethylene terephthalate) substrates (1.1 × 107 S m-1) corresponding to 43\% and 18\% of the bulk silver conductivity. Conducted tape tests show the suitability of the ink for particularly polymer substrates. TG-MS studies demonstrate a two-step decomposition for the conversion of 3 to elemental silver. The structure of 3 in the solid state was determined by single X-ray structure determination.}, language = {en} } @misc{MuellerSchwarzSchmidtetal., author = {M{\"u}ller, Carola J. and Schwarz, Ulrich and Schmidt, Peer and Schnelle, Walter and Doert, Thomas}, title = {High-Pressure Synthesis, Crystal Structure, and Properties of GdS2 with Thermodynamic Investigations in the Phase Diagram Gd-S,}, series = {Zeitschrift f{\"u}r anorganische und allgemeine Chemie}, volume = {636}, journal = {Zeitschrift f{\"u}r anorganische und allgemeine Chemie}, number = {6}, issn = {1521-3749}, doi = {10.1002/zaac.201000015}, pages = {947 -- 953}, abstract = {Gadolinium disulfide was prepared by high-pressure synthesis at 8 GPa and 1173 K. It crystallizes in the monoclinic space group P121/a1 (No. 14) with lattice parameters a = 7.879(1) {\AA}; b = 3.936(1) {\AA}, c = 7.926(1) {\AA} and β = 90.08(1)°. The crystal structure is a twofold superstructure of the aristotype ZrSSi and consists of puckered cationic [GdS]+ double slabs that are sandwiched by planar sulfur sheets containing S22- dumbbells. The thermal decomposition of GdS2 proceeds via the sulfur-deficient polysulfides GdS1.9, GdS1.85 and GdS1.77 and eventually results in the sesquisulfide Gd2S3. GdS2 is a paramagnetic semiconductor which orders antiferromagnetically at TN = 7.7(1) K. A metamagnetic transition is observed in the magnetically ordered state.}, language = {en} }